1. Field of the Invention
This invention applies to the industry concerned with guidance and propulsion of heavy loads from place to place about a floor in an industry where loads levitate upon a pressurized fluid caster during transport. More particularly, this invention integrates a fluid levitated caster with an external debris scraper.
2. Description of Prior Art
In the fluid caster industry of my invention, a load levitates near frictionless upon multiple fluid casters attached beneath the load. It often takes surprisingly low forces to move the levitated load. On flat floors, relatively smaller loads move by an operator pushing or pulling the load by hand. The low force required to move the levitated load is a major advantage for utilizing fluid caster methodology to move heavy loads.
Fluid caster movement upon floors covered with debris such as nails, sand, screws, nuts, metal chips can be problematic. While inflated, the fluid caster levitation membrane is in near physical contact with the floor surface (usually a couple of thousands of an inch above the floor surface). A debris object squeezed between the floor surface and the levitation membrane surface (if large enough) can cause sufficient air leakage out of the membrane to cause enough friction between the membrane floor to halt movement. Additionally, if the debris particle is large and sharp, it can cut through the levitation membrane rendering it useless. For these reasons, operators of fluid levitated casters take came to carefully sweep the floor clean of debris before use. Sometimes debris particles can be overlooked. It is advantageous for the fluid levitated caster to be able to sweep aside floor debris, keeping it away from the levitation membrane. It is an object of my invention to integrate the fluid levitated caster with an external debris scraper.
Numerous inventors have patented various configurations of fluid levitated casters from about the 1960""s and on. However, none of these patents mention the inclusion of a scraper ring which sweeps aside potentially caster damaging floor surface debris. U.S. Pat. No. 3390736 by Thomas, Jun. 28, 1966 shows a very representative fluid caster patent. This levitation caster shows a levitation membrane 22 in contact (or near contact) with the floor surface 30. Note there exists controlled air (fluid) leakage flowing between the levitation membrane 22 and the floor surface 30 creating near-frictionless load transport. The same view also shows the fluid caster frame 34 raised or levitated off floor surface 30 by an amount equal to the levitation membrane 22 lift (as caused by automobile inner tube like air inflation). In this patent (as all others in this industry), it is clear that no structure element exists to sweep away any debris from the floor surface 30. It is also clear from this patent, that any debris on the floor surface 30 could end up under the floor contact portion of the levitation membrane 22 as the fluid caster translates or moves laterally. Such floor debris as sharp metal chips can cut through levitation membranes rendering them useless. Larger floor debris such as screws, nuts, and the like can produce a gap between the flexible levitation membrane 22 and floor surface 30 causing lubrication fluid to escape, creating friction between floor surface 30 and levitation membrane 22, therefore halting load movement.
A cited unpatented fluid levitated caster product is marketed which includes an internal debris scraper ring. The product utilizes the scraper ring both as a debris sweeper and as the levitation membrane. The scraper ring sweeps aside debris objects well, but is not very effective as a levitation membrane. For effective and practical levitation, the levitation membrane should be very compliant to conform to floor imperfections such as pits, cracks, flatness undulations etc. Lack of compliance of the levitation membrane results in poor air sealing with the local floor surface. Poor air sealing can lose the advantage of near frictionless movement force. It""s use is like moving levitated loads across the floor with xe2x80x9cbrakes onxe2x80x9d! Even more importantly, the poor air sealing between the floor and the scraper ring necessitates larger air flows and consumption in order that the load stay levitated. With identical air supply flow rates and levitated loads, this fluid caster with internal scraper ring as compared to typical fluid casters without a scraper ring requires a near perfect floor to perform similarly. With real life floor conditions and imperfections, fluid casters without scraper ring can move loads with far less friction, and with far less air consumption.
My invention has the advantage over conventional fluid casters in that it includes an external scraper to sweep aside floor debris so it won""t cut levitation membrane or cause friction between levitation membrane and floor surface. My invention has the advantage over the above cited fluid caster with internal scraper ring in that it retains the near-frictionless fluid caster advantage, and requires far less air consumption and flow rate.
My invention integrates a fluid caster with an external scraper ring into a single assembly. This invention results in a unique device that not only efficiently levitates with near-frictionless a heavy load for transporting, but can also sweep aside floor debris such as nails, sand, screws, nuts, metal chips. This added function prevents debris from causing friction between floor surface and levitation membrane or from cutting the levitation membrane. The scraper ring is external to the levitation membrane, thereby being able to sweep away debris before the debris reaches the levitation membrane area The external scraper ring can be slideably attached to the fluid caster subassembly frame so the scraper ring can move vertically in unison with the levitation membrane vertical lift movement. A separation force between the fluid caster subassembly frame and the scraper ring can insure that the scraper ring is always in forced floor contact sweeping away debris. This downward force on scraper ring can be created in many ways including: gravity pull on heavy weight, spring, fluid pressure/air bag, fluid pressure/piston and cylinder, etc.
The scraper ring design can also assume many embodiments including, but not limited to: ring with brush fibers attached, ring with flexible strip attached, ring with replaceable wear surface attached, ring scrape surface shaped in one of many advantageous configurations conforming to particular floor debris conditions, ring material constructed of one of many materials conforming to particular floor/debris conditions, ring with motorized sweeping rotation, and ring made from several ring segments.
Operators of prior art fluid caster transport systems typically inspect and sweep every square inch of the floor surface over which the load is to be moved to insure all debris is removed. Operators using the fluid casters of my invention need not be concerned that typical unremoved debris will cut through the levitation membrane.
My invention is not appreciably larger in physical size, in weight, nor in cost than that of prior art fluid casters alone. Therefore cost advantages can be realized considering minimizing or eliminating operator floor sweeping and floor inspection labor costs.
An unexpected advantage of my invention is that operator oversight of not finding or not cleaning some floor debris does not result in levitation cut failure.